Cecilia Payne-Gaposchkin ( 1900 - 1979)

Cecilia Helena Payne-Gaposchkin (née Payne) was a British-born American astronomer and astrophysicist who proposed in her 1925 doctoral thesis that stars were composed primarily of hydrogen and helium. Her groundbreaking conclusion was initially rejected because it contradicted the scientific wisdom of the time, which held that there were no significant elemental differences between the Sun and Earth. Independent observations eventually proved she was correct. Source: Wikipedia

Cecilia Payne’s mother refused to spend money on her college education, so she won a scholarship to Cambridge.

Cecilia Payne completed her studies, but Cambridge wouldn’t give her a degree because she was a woman, so she said to heck with that and moved to the United States to work at Harvard.

Cecilia Payne was the first person ever to earn a Ph.D. in astronomy from Radcliffe College, with what Otto Strauve called “the most brilliant Ph.D. thesis ever written in astronomy.”

Not only did Cecilia Payne discover what the universe is made of, she also discovered what the sun is made of (Henry Norris Russell, a fellow astronomer, is usually given credit for discovering that the sun’s composition is different from the Earth’s, but he came to his conclusions four years later than Payne—after telling her not to publish).

Cecilia Payne is the reason we know basically anything about variable stars (stars whose brightness as seen from earth fluctuates). Literally every other study on variable stars is based on her work.

Cecilia Payne was the first woman to be promoted to full professor from within Harvard, and is often credited with breaking the glass ceiling for women in the Harvard science department and in astronomy, as well as inspiring entire generations of women to take up science. Source: Twitter stream by @AishaRashwan

Known for
Explanation of stellar spectra and composition of the Sun

More than 3,000,000 observations of variable stars

First person to earn a PhD in astronomy from Radcliffe College

Her observations and analysis of variable stars, carried out with her husband, Sergei Gaposchkin, laid the basis for all subsequent work on such objects

Payne-Gaposchkin remained scientifically active throughout her life, spending her entire academic career at Harvard. When she began, women were barred from becoming professors at Harvard, so she spent years doing less prestigious, low-paid research jobs. Nevertheless, her work resulted in several published books, including The Stars of High Luminosity (1930), Variable Stars (1938) and Variable Stars and Galactic Structure (1954). Mentor Harlow Shapley had made efforts to improve her position, and in 1938 she was given the title of "Astronomer". On Payne's request, her title was later changed to Phillips Astronomer.

Find more
Wikipedia

Cecilia Payne-Gaposchkin: an autobiography and other recollections

"Sisters of the Sun", eighth episode of Cosmos: A Spacetime Odyssey, 2014 American science documentary television series